Positive regulation of T-even-phage DNA replication by the DNA-delay protein of gene 39.
Positive regulation of T-even-phage DNA replication by the DNA-delay protein of gene 39.
复制标题
基因 39 的 DNA 延迟蛋白对 T 偶数噬菌体 DNA 复制的正调控。
DOI：
10.1101/sqb.1979.043.01.055
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发表时间：
1979
期刊：
影响因子：
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通讯作者：
W. Huang
中科院分区：
文献类型：
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作者：
W. Huang
大型噬菌体T4的DNA复制是一个非常复杂的过程，这由至少20个参与DNA复制和DNA代谢的必需噬菌体基因的存在所指示。其中包括基因39、52和58，它们由一组称为”DNA延迟”突变体的突变体定义。这些突变体的特征在于噬菌体DNA复制开始的延迟，并且在这些基因产物中的任何一种不存在的情况下，噬菌体DNA复制不被消除。这种表型不同于T4的其他六种DNA复制蛋白，这些蛋白以前在遗传学和生物化学上被认为是链延长和叉运动合成过程中绝对需要的直接参与者（Warner和Hobbs 1967; Alberts等1975）。最近，通过使用SDS-聚丙烯酰胺凝胶电泳，我们已经表明两种T4 DNA延迟蛋白，基因39和52的蛋白（单体分子量分别为64，000和51，000）与细菌膜相关（Huang 1975），并且有证据表明T4 DNA复制发生在膜上（Siegel和Schaechter 1973）。此外，通过DNA纤维素层析，这两种蛋白质也显示出与DNA紧密结合（Huang和Buchanan 1974）。DNA延迟突变体的表观表型和DNA延迟蛋白的物理性质表明，这些基因产物可能参与了起始DNA复制的过程。在噬菌体T4的体内复制中，即使在大量过量的细菌DNA存在下，受感染的细胞也选择性地和排他地复制病毒基因组。虽然T4确实诱导特异性降解细菌宿主DNA的核酸酶，但去除其他类型的DNA不能成为赋予待在细胞中复制的DNA模板特异性的快速有效的方法。此外，已经分离出T4的突变体，其中宿主DNA的分解是最小的，但噬菌体DNA的特异性复制仍然发生（Hercules等，1971）。因此，预期在感染的细胞中存在能够特异性选择T4 DNA进行复制的阳性决定簇。构成链延伸和分叉运动的合成装置的T4复制蛋白显然可以以相同的效率利用各种DNA模板（Liu et al.，此卷）。因此，它们不太可能是正决定簇的候选者。在本文中，我提出的证据，
DNA replication of the large bacteriophage T4 is a very complex process as indicated by the existence of at least 20 essential phage genes involved in DNA replication and DNA metabolism. Among these are genes 39, 52, and 58, which are defined by a set of mutants called" DNA-delay" mutants. These mutants are characterized by a delay in the onset of phage DNA replication, and in the absence of any one of these gene products, phage DNA replication is not abolished. This phenotype is different from that of the other set of six DNA-replication proteins of T4 which were previously recognized genetically and biochemically as absolutely required as direct participants in the synthetic process of chain elongation and fork movement (Warner and Hobbs 1967; Alberts et al. 1975). Recently, by using SDS-polyacrylamide gel electrophoresis, we have shown that two of the T4 DNA-delay proteins, the proteins of genes 39 and 52 (monomeric molecular weights of 64,000 and 51,000, respectively) are associated with the bacterial membrane (Huang 1975), and there is evidence that T4 DNA replication occurs on the membrane (Siegel and Schaechter 1973). Furthermore, by means of DNA cellulose chromatography, these two proteins have also been shown to bind DNA tightly (Huang and Buchanan 1974). The apparent phenotype of the DNA-delay mutants and the physical properties of the DNA-delay proteins suggest that these gene products may be involved in the process of initiating DNA replication at the origin. In the in vivo replication of phage T4, the infected cells selectively and exclusively replicate the viral genome even in the presence of a large excess of bacterial DNA. Although T4 does induce nucleases which specifically degrade bacterial host DNA, removal of other types of DNAs cannot be a rapid and efficient way to confer template specificity on the DNA to be replicated in a cell. Furthermore, mutants of T4 have been isolated in which the breakdown of host DNA is minimal, yet specific replication of phage DNA still occurs (Hercules et al. 1971). Therefore, it is expected that a positive determinant capable of selecting specifically T4 DNA for replication is present in the infected cells. The T4 replication proteins which constitute the synthetic apparatus of chain elongation and fork movement apparently can utilize a variety of DNA templates with equal efficiency (Liu et al., this volume). Therefore, it is unlikely that they are the candidates for the positive determinant. In this paper, I present evidence that